[R] Cox regression and p-values

[Marc Schwartz]

I'll throw in a more recent citation:

Chi-squared and Fisher-Irwin tests of two-by-two tables with small
sample recommendations
Stat in Med 26:3661-3675; 2007
http://www3.interscience.wiley.com/cgi-bin/abstract/114125487/ABSTRACT

to which Frank Harrell has offered some comments here (bottom of page):

  http://biostat.mc.vanderbilt.edu/twiki/bin/view/Main/DataAnalysisDisc

HTH,

Marc Schwartz


On Tue, 2007-09-18 at 11:08 -0700, Cody Hamilton wrote:
> Daniel,
> 
> With regards to the use of Fisher's exact test when cell counts are
> less than 5, take a look at:
> 
> D'Agostino, RB, Chase, W and Belanger, A (1988). 'The appropriateness
> of some common procedures for testing the equality of two independent
> binomial populations.' 42:198-202.
> 
> Regards,
>    -Cody

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Daniel Brewer
> Sent: Tuesday, September 18, 2007 9:42 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Cox regression and p-values
> 
> Hello,
> I might be barking up the wrong tree here, but I want to make sure I
> have a full understanding of this.  What I would like to know is what
> tests are performed to give the p-values for each variable in the table
> that is the result of coxph regression when the variables are
> categorical only.
> 
> More specifically, when expected counts are less than 5 is the Fisher's
> exact test used instead of the Chi^2 test?
> 
> Many thanks
> Dan